Why is the model grey?

Because STL stores no colour, materials or texture coordinates — only the mesh. The USDZ inherits exactly that. To reach AR with colour you need to start from an OBJ, GLB or glTF with textures.

Is it good for showing a part at real scale?

Yes, and that's the most useful case: Quick Look places the model on the floor or a table at its actual size. Since STL comes in millimetres and USD works in centimetres, the conversion applies the factor so measurements hold.

Can I go back from USDZ to STL?

Yes: USDZ is now an input format too — load it in the converter and choose STL as output. Still, keep the original STL: that's the file your slicer needs to print.

No file handy?

Convert toUSDZ

Coordinates and scale are preserved exactly as they are.

Convert STL to USDZ

Drop your STL files and download them as USDZ: free, in batch, and they never leave your device.

STL → USDZ: what you should know

STL to USDZ takes a model built for printing into Apple's augmented reality format: instead of sending a file the other person can't open, you send a USDZ that any iPhone shows with a single tap.

It's the most direct way to show a part to someone with no 3D software — a client, a colleague, a teacher. STL stores only triangles, no colour and no materials, so the USDZ comes out grey: pure geometry, exactly like the original.

The conversion happens entirely in the browser. Your STL is never uploaded.

Related conversions

STL → PLY STL → OBJ STL → GLB STL → 3MF PLY → USDZ OBJ → USDZ glTF → USDZ GLB → USDZ

Analytics

I measure which tools get used and which ones fail, so I can fix them. Your files never leave your device.

If you decline, everything still works. If you answer a question, I only keep your answer. What I measure